Getting Back Into It....

Hi,
I am a 21 yr. old male, recovering from "prostatis and some rotator cuff injury. Before these problems I weighed in at approx. 190 I know weigh at 175. I went back to the gym yesterday and did a chest/tricep routine. The weight loss I suffered does not bother me too much due to the fact that I seem to have lost a tremendous amount of fat and my chest seems to be more defined. I have been working out on and off for around 4 yrs. now. My stats are 5'11 175lbs, and unfortunately I am not aware of my bf%. My goals are instead of just getting real big and what not, Is to try and cut some of the fat down while gaining more "lean" muscle mass. My normal routine is as follows any suggestions on changing it, or mixing things up a little would be appreciated. -
day 1 - chest/triceps - 3 sets reps 12, 8, 4-6
day 2- biceps/back - 3-4 sets reps 15, 10, 8, 4-6
day 3 - shoulders, rear delt, traps - 3 sets reps 10, 8, 4-6
day 4 - legs and abs - 3 sets legs - reps 12, 10, 8,
Before each workout I incorporate around 5 minutes of full body stretching and then jump on the tread for a 5 minute warmup. Then I start my routine and am usually done within 40 - 60 minutes. After that I stretch again, and jump back on the tread. for around 10-15 minutes. Then I hit the shower. My shoulders suffer from severe instability and I am on my way to see an Orthopedic surgeon In the following week. Since I am trying to stay out of the operating room, any suggestions on trying to tighten the rotator cuff muscles to keep my shoulder in a more stable position would be a great help to me.
Thankyou for your time.
Patrick.

Sorry guys....I didn't include all the info. the areas I would most likely like to build on are obviously my shoulders, chest, traps, lats, and legs. Should I stay lifting heavy like my workout routine does or since I would like to cut but stay lean Is their any other way to administer sets or reps ?
Thanx again
Patrick

try reps of 12 10 8 10 12

and lowering that weight till your shoulder is 110%

and strict form !